The advising relationship has been acknowledged as one of the most important factors in doctoral student persistence and attrition. Less researched are psychosocial factors that contribute to doctoral student persistence and completion. Preliminary research including measures of psychosocial factors on doctoral student success found faculty-student relationships and collegial support contributed significantly to doctoral completion more so than individual factors including motivation, career goals, procrastination, financial security, and external demands such as family. The current study draws on the psychosocial construct of mattering (Rosenberg & McCullough, 1981) to examine doctoral students' perceptions of mattering to their advisors and the influence on their commitment to complete their PhD. Using a qualitative multiple case study approach, findings from this study revealed the impact of the discipline on the advisor-student relationship, particularly in how mattering is experienced and the influence on students' commitment to complete the PhD. Three components of mattering were examined: attention, importance and dependence. While a new form of attention emerged from both cases, this form of attention manifested in different ways for each case. Findings from this study revealed students in one case felt their relationships with their advisors confirmed their commitment, while the same conclusion was not supported within the other case. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]